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Metabolism & Weight Management

Is the hCG Diet the Secret for Weight Loss? Does it Really Work?

The hCG diet was introduced in the 1950s and, since its inception, has been considered controversial.

The hCG diet combines a very low calorie diet – typically 500 cal per day – with the daily injection of human chorionic gonadotropin (hCG).  Many proponents claim that following the diet can result in an average weight loss of up to 1lb per day for up to a month. The diet was developed by A.T.W. Simeons, M.D. based on his obesity research and seemingly extensive experience using the hormone successfully.

How does it work?

hCG is a hormone that is produced by the placenta during pregnancy.  Its function, at least in part, is to support fetal development by assuring that energy is maximally mobilized so that it is available to the growing fetus.  It seems to do this by affecting the structures of the diencephalon, a part of the primitive brain that controls automatic functions in the body.  Fat metabolism and storage is one such function.

One of the theories of obesity is that the diencephalon can be overwhelmed by excessive stressors or imbalances (such as overeating, sedentary lifestyles, hormone imbalances, psychological or emotional stressors, etc.) such that it becomes reset to a level that is more tolerant to the inefficient use and storage of fat.  This typically happens in our late 30s or early 40s but can start as early as our late 20s, when perhaps our caloric intake remains unchanged but our level of daily exercise decreases significantly.  It can also happen as a consequence of our hormone levels and balance deteriorating starting as early as our 30s.

It is no coincidence that this is when most people start to experience an increase in weight gain, especially in areas such as the hips and belly, which are neither normal nor healthy areas of fat storage.

Dr. Simeons explained that there are 3 types of fat:

  1. Structural fat (such as the fat pad of our feet and hands as well as the insulating fat of our organs)
  2. Normal fat (stored for energy)
  3. Abnormal fat (stored unnecessarily)

Abnormal fat is the type that accumulates in the abdomen (especially in men) and hips (especially in women), and is a reflection of excessive caloric intake and/or imbalances of metabolism from any number of underlying conditions.  The problem with the storage of abnormal fat is that because it is the product of abnormal metabolism, it is not easily accessible to or re-mobilized by the body for fuel.  In other words, the abnormal fat accumulates, but the body is less able to access and use it for energy (as it does with normal fat deposits).

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Low calorie diets and excessive exercise do little to help the situation because they further stress the body, thereby worsening an already aberrant metabolism.  Instead of using abnormal fat, the body will metabolize structural fat, normal fat, and even muscle tissue. This leads to decreased amounts of supportive and necessary fat (resulting in aches and pains in the joints) and muscle loss.

In theory, the use of hCG does two things to circumvent this problem.  By affecting the primitive control centers in the brain, it decreases hunger such that individuals can maintain very low calorie diets without hunger.

In addition, through mechanisms that are not yet completely understood, it makes abnormal fat more accessible and usable to the body, and this is the primary reason why it is produced during pregnancy.

In this way hCG acts as a key that unlocks access to energy in otherwise abnormal fat stores and therefore provides additional energy to a growing fetus; or, in the case of an hCG dieter, allows the individual to access and burn their abnormal fat.  The diet works by having the body run on this now accessible energy (anywhere from 1400-7000 calories per day) wherein it is burning off what is otherwise stagnant and persistent body fat while simultaneously preserving normal and structural fat as well as muscle.

hcg diet

The diet combines a very low calorie diet – typically 500 cal per day – with the daily injection of human chorionic gonadotropin (hCG)

Does the hCG DIET work?

Although the effects of the hCG diet were supported by Dr. Simeons’ documented experiments and treatments in addition to a randomized double blinded study by Asher and Harper on 40 subjects in 1973, numerous, larger studies have failed to replicate and validate these results.  In these studies, Simeons’ strategy when reproduced did not seem to benefit the subjects better than placebo.  As it currently stands, the scientific evidence stacks strongly against the hCG diet as an effective means for weight loss.  (2-10)

However, a great deal of anecdotal experience – including my own professional experience with the diet – seems to contradict these studies.  The results that I personally have witnessed, though admittedly with a relatively small subset of patients (roughly 50), have been impressive.  In the small cohort with whom I have worked, the typical result is weight loss of anywhere from 12-20 lbs.

But why would a diligent and responsible physician or practical patient even consider experimenting with a study that conventional medicine clearly rejects? Because it seems to work in selected patients and there is very little downside in trying.  In contrast, many commonly used medications for obesity and other conditions have side effects that are potentially far more harmful.  At the end of the day, every treatment decision that a patient and physician make together should be a fair and balanced evaluation of the potential risks and benefits of the treatment.

Risks, downsides or side effects of the HCG Diet?

Research any common medication and you are bound to find numerous potential side effects and even whole websites or societies dedicated to sharing horror stories.  The case is no different for hCG except that the potential harm is usually discussed in generalities and is mostly linked to concerns regarding a low-calorie diet.  Concerns in the literature include fatigue, irritability, restlessness, depression, fluid retention, swelling, and more concerning problems such as blood clots and cancer.  But on fair and balanced review of the evidence, the concern for worrisome side effects is minimal and in practice I have not seen my patients experience any significant side effects.

Work with a Parsley doctor to help you find and monitor the right diet program for your body.


As physicians dedicated to working with the best science available, the physicians of Parsley Health do not typically or routinely endorse or suggest the use of hCG along with very low calorie diets because of the low level of evidence in support of its safe and effective use.

However, as practical physicians who are aware of the lack of significant evidence of harm, we could potentially consider the hCG diet as part of a more comprehensive, holistic weight management program as long as it is conducted under the supervision of both an experienced physician and nutritionist.  In the appropriately selected patient, hCG may be a reasonable consideration.  Such a patient would be one that is likely to change their dietary behaviors long-term so as to not undo the benefits of treatment afterwards.  A very low calorie diet is typically neither necessary nor recommended for most.  A more reasonable and safe approach (although somewhat less dramatic in effect) would be to use hCG for its potential ability to affect abnormal fat loss in conjunction with a low-calorie diet (usually 1000-1200 calories).  hCG should only be used as prescribed, under physician supervision, and with a plan that includes specific, individual nutritional prescriptions to assure better safety and efficacy.


  1. Pounds & Inches: A New Approach to Obesity – A.T.W. Simeons, Salvator Mundi International Hosptial L 00152 -Rome Viale Mura Gianicolensi, 77
  2. Evidence for, and Associated Risks with, the Human Chorionic Gonadotropin Supplemented Diet. J Diet Suppl. 2016 Nov;13(6):694-9. doi: 10.3109/19390211.2016.1156208. Epub 2016 Mar 24. Butler SA1, Cole LA2.
  3. Human chorionic gonadotrophin and weight loss. A double-blind, placebo-controlled trial. Bosch B1, Venter I, Stewart RI, Bertram SR. S Afr Med J. 1990 Feb 17;77(4):185-9.
  4. Human chorionic gonadotropin (HCG) in the treatment of obesity: a critical assessment of the Simeons method. Greenway FL, Bray GA. West J Med. 1977 Dec;127(6):461-3.
  5. Human chorionic gonadotropin (HCG) treatment of obesity. Shetty KR, Kalkhoff RK.,  Arch Intern Med. 1977 Feb;137(2):151-5.
  6. Chorionic gonadotropin in weight control. A double-blind crossover study. Young RL, Fuchs RJ, Woltjen MJ. JAMA. 1976 Nov 29;236(22):2495-7.
  7. Ineffectiveness of human chorionic gonadotropin in weight reduction: a double-blind study. Stein MR, Julis RE, Peck CC, Hinshaw W, Sawicki JE, Deller JJ Jr. Am J Clin Nutr. 1976 Sep;29(9):940-8.
  8. Ineffectiveness of human chorionic gonadotropin in weight reduction: a double-blind study. Stein MR, Julis RE, Peck CC, Hinshaw W, Sawicki JE, Deller JJ Jr. Am J Clin Nutr. 1976 Sep;29(9):940-8.
  9. Human chorionic gonadotropin (HCG) in the treatment of obesity: a critical assessment of the Simeons method. Greenway FL, Bray GA. West J Med. 1977 Dec;127(6):461-3.
  10. Effect of the human chorionic gonadotropin diet on patient outcomes. Goodbar NH1, Foushee JA, Eagerton DH, Haynes KB, Johnson AA. Ann Pharmacother. 2013 May;47(5):e23. doi: 10.1345/aph.1R755. Epub 2013 Apr 19.

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